Abstract:

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In this work, we present the novel robust material, modified natural rubber (NR) composites filled with gold nanoparticles (AuNPs). To investigate its outstanding properties, dielectric, electrical and mechanical properties of NR and modified NR composites filled with gold nanoparticles (AuNPs) were studied. The NR and all composite films were prepared by using solution casting method. The size of the synthetic AuNPs was analyzed by Transmission Electron Microscope (TEM) technique. The dispersion of AuNPs fillers within the NR matrix was investigated by scanning electron microscopy (SEM). Dielectric and electrical properties of NR composites were analyzed as function of filler concentration and frequency in a range of 100-105 Hz, observed with the LCR analyzer. Elastic modulus of all samples was evaluated by a strain gauge set up. It was found that the dielectric constant is inversely related to the frequency. Moreover, the dielectric constant and the electrical conductivity strongly increase in proportional to the AuNPs filler content. In comparison at AuNPs concentration of 0.0010% by weight, it was observed that the dielectric constant of NR composites is eight times larger than the pure NR, while the mechanical properties of the NR composites slightly increase in proportional to the AuNPs. As consequence, the interfacial surface area significantly affects the electrical and mechanical properties of those NR composites.

Abstract: Titanium metal matrix composites were produced. The powder metallurgy route applied
was a conventional route consisting of blending titanium matrix powder with different percentages
of various titanium compounds, as reinforcement particles, followed by cold compaction in a
uniaxial press with a floating matrix and a sintering process in a vacuum furnace. This work studied
the different interactions between the titanium matrix and the various titanium compounds added.
To evaluate these interactions microscopic techniques are used principally, optical and electronic
microscopy, with EDX techniques. By microstructural analysis the reactivity between
reinforcement and matrix particles was investigated, and any new phases that formed during the
sintering process were evaluated. In addition, microhardness test were conducted to study the
mechanical properties associated with the new phases, and to evaluate the relative strength or
weakness of the interfacial zones.

Abstract: In this paper, electron beam radiation technology was applied to the preparation of MMT/MWNTs/epoxy nano-composites. The influences of the addition of Montmorillonite (MMT) and multi-walled carbon nanotubes (MWNTs) on the tensile properties of MMT/MWNTs/epoxy nano-composites were examined. The fracture surface of the composites was characterized by SEM as well. The results indicated that the composites have higher tensile modulus than that of the pristine epoxy resin.

Abstract: Blends of Poly(L-lactide) (PLLA) and nano-SiO2 powder were prepared via solution mixing. Effect of nano-SiO2 particles on the crystallinity of PLLA in composite was investigated by X-ray diffraction, the result indicated that the incorporation of nano-SiO2 did not influence the crystallinity of PLLA in composite. The bending strength and modulus of the PLLA/nano-SiO2 composites with varying nano-SiO2 content were tested, showing that the bending strength reduced with the increase of nano-SiO2 content and the bending modulus increased. The SEM graphs of PLLA/nano-SiO2 composites were illustrated that the cross-section of composites varied from brittle to ductile fracture with the content of nano-SiO2 increasing up to 10 %, and changed from ductile to brittle fracture with further increasing of nano-SiO2 content.

Abstract: Among the broad class of electro-active polymers, dielectric elastomer actuators represent a rapidly growing technology for electromechanical transduction. In order to further develop this applied science, the high driving voltages currently needed must be reduced. For this purpose, one of the most promising and adopted approach is to increase the dielectric constant while maintaining both low dielectric losses and high mechanical compliance. In this work, a dielectric elastomer was prepared by dispersing functionalised carbon nanotubes into a polyurethane matrix and the effects of filler dispersion into the matrix were studied in terms of dielectric, mechanical and electro-mechanical performance. An interesting increment of the dielectric constant was observed throughout the collected spectrum while the loss factor remained almost unchanged with respect to the simple matrix, indicating that conductive percolation paths did not arise in such a system. Consequences of the chemical functionalisation of carbon nanotubes with respect to the use of unmodified filler were also studied and discussed along with rising benefits and drawbacks for the whole composite material.

Abstract: Composites made from phenolic resin are filled with conductive filler mixtures containing copper powders, natural graphite powders and carbon fibers. They are fabricated by compression molding technique. The density, electrical conductivity and hardness of composite are analyzed to determine the influence of copper particle size on the physical, electrical and mechanical properties of composite. It is found that there is a marked dependence of the electrical conductivity and hardness on copper particle size. The hardness decreases with the decreasing of copper particle size. However the electrical conductivity increases with the decreasing of copper particle size. The decreasing of copper particle size from 75 µm to 48 µm promotes a considerable increase in electrical conductivity by about 427%. The increased continuous conductive metal networks could be the main reason for the increasing of electrical conductivity as copper particle size decreases. The results also show that composites containing copper particles of different sizes have the nearly same density.